Triple Junction Mobility: A Molecular Dynamics Study |
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| Authors: | Moneesh Upmanyu DJ Srolovitz LS Shvindlerman G Gottstein |
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| Institution: | (1) Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA; and;(2) Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA;(3) Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 08544, USA; and;(4) Princeton Materials Institute, Princeton University, Princeton, NJ 08544, USA;(5) Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow distr, 142432, Russia; and;(6) RWTH Aachen, Institut für Metallkunde und Metallphysik, D-52056 Aachen, Germany;(7) RWTH Aachen, Institut für Metallkunde und Metallphysik, D-52056 Aachen, Germany |
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| Abstract: | We present a molecular dynamics simulation study of the migration of individual grain boundary triple junctions. The simulation cell was designed to achieve steady state migration. Observations of the triple junction angle and grain boundary profiles confirm that steady state was achieved. The static, equilibrium grain boundary triple junction angles and the dynamic triple junction angles were measured as a function of grain size and grain boundary misorientation. In most cases, the static and dynamic triple junction angles are nearly identical, while substantial deviations were observed for low  boundary misorientations. The intrinsic, steady-state triple junction mobilities were extracted from measurements of the rate of change of grain boundary area in simulations with and without triple junctions. The triple junction velocity is found to be inversely proportional to the grain size width. The normalized triple junction mobility exhibits strong variations with boundary misorientation, with strong minima at misorientations corresponding to orientations corresponding to low values of . The triple junctions create substantial drag on grain boundary migration at these low mobility misorientations. |
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| Keywords: | triple junction mobility thermodynamic equilibrium grain boundary energy grain boundary migration static and dynamic triple junction angles steady-state triple junction migration special (high coincidence) boundaries triple junction drag |
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